The present invention relates to an extraction machine for underground ore extraction operations with extraction of the product by blasting, with an advancing support unit and a face conveyor coupled to it and with at least one boring device for the production of holes for explosive and a loading device for loading the conveyor with the blast rock loosened by blasting. The present invention further relates to a method for extracting output products in underground mining by blasting in the face with the use of an advancing support equipment and a face conveyor coupled to this and at least one boring device for the production of holes for explosive and a loading device for loading the face conveyor with the blast rock loosened by blasting.
An extraction machine for the extraction of ore-bearing rock using blasting is proposed in DE 197 21 201 A1, in which the blast rock is conveyed out of the extraction face with the aid of a face conveyor. The face conveyor comprises here a chain scraper conveyor, whose return run is arranged sideways at a distance from its conveying run, behind it and whose driven and endless scraper chain, reversible over chain wheels into conveying and return runs is guided in a chain guide channel, whereby the two chain guide channels are arranged at a distance sideways from each other. On the face conveyor itself is arranged a boring device which can move along the face, which bores the necessary holes in the face, running at right angles to the direction of mining. The loading of the conveyor with the blast rock loosened by the blasting is effected by shifting the conveyor so that the conveyor pan, wedge shaped toward the face, facing the working face is pushed along the ground into the loosened blast rock, which then comes into the working area of the moving scrapers, and is taken away out of the face.
The boring of shot holes, which are made in the direction of the mining into the rock face running at right angles to this, makes it difficult if not entirely impossible to maintain a level floor or roof. This leads to the condition that the blast rock loosened by the blasting can be loaded onto the then advanced conveyor only with difficulty and with relatively large loss, since the floor is so uneven that a large part of the loosened blast rock remains under the wedge shaped loading pans.
A boring wagon for application in a generic extraction machine is known from DE-B-970 161, which is withdrawn onto an auxiliary travelling frame after boring the shot holes, so as thereby to provide sufficient space for a face shovelling loader to load the loosened blast rock and then to transport it to a loading band beginning behind the face shovelling loader.
It is the aim of the present invention to produce an extraction machine of the construction described in the opening paragraph, with which it is possible to achieve a very smooth and even quality of the roof and floor ore extraction operations and therewith actually to extract the greatest possible proportion of the loosened blast rock. In this the expenditure on machinery should be kept low and the machines brought into application are exploited as fully as possible.
Accordingly the present invention is directed to an extraction machine as described in the opening paragraph of the present specification in which, the boring device and the loading device are assigned to a boring and loading machine, which can travel along the face conveyor at right angles to the direction of mining towards the rock face running parallel to the direction of mining or away from this.
Differently from the mining method proposed in DE 197 21 201, the necessary shot holes for the blasting are not bored into the face parallel to the mining direction but at right angles to the direction of mining into a comparatively narrow rock face, which runs parallel to the direction of mining. To this end the boring machine provided with the boring device is advanced along the face conveyor into the face until the shot holes can be bored. After the boring the whole boring pattern, the boring equipment can be withdrawn from the rock face until it is again in the safe zone when, after the setting of the blast charges, blasting occurs. During the setting of the blasting charges the boring equipment can be exchanged for the loading equipment or can be so converted to a loading equipment that the loading device can be applied, so that the machine provided with the loading equipment can be advanced without delay after the explosion is complete so as to convey the blast rock loosened by the explosion using the loading equipment onto the face conveyor.
The arrangement of the bored holes, which are bored at right angles to the direction of mining permit, with a suitable choice of a matching boring pattern, a very even floor and roof to be obtained, which substantially eases the advance of the conveyor and the stepping of the mining machine. Furthermore with this method of operation the greater part of the loosened blast rock is actually loaded onto the face conveyor and extracted. The boring device and/or the loading device is/are preferably demountably arranged on a common boring and loading machine. The boring device can be removed from the common boring and loading machine after boring the shot holes and stored temporarily at a suitable position, whilst the equipment with the loading device loads the loosened blast rock onto the conveyor.
Especially on comparatively short faces, where the distance from the face end side path to the rock face is not more than 100 m, it can be expedient if the boring device and the loading device are each arranged on separate movable boring or loading machines. In this configuration it is not necessary after each withdrawal of the equipment fitted out with the boring or loading equipment for this to be converted to the other device in each case, so that no conversion times delay the advance of the mining.
An advantageous arrangement results if the loading device has a side loading shovel, whereby the boring unit can be demountably connected onto the loading device.
The face conveyor can be equipped with at least one additional boring device which can move in its longitudinal direction, with a height adjustable boring carriage with which in addition to the borings made in the longitudinal direction of the face shot holes can also be bored in the direction of mining. By this simultaneous boring both parallel to the longitudinal direction of the face from the rock face out and also at right angles to it, the time which the boring process takes overall is shortened considerably. It is especially expedient in this method of operation to cause the boring device boring parallel to the longitudinal direction of the face on the travelling boring equipment to bore the holes in the floor and the roof of the rock face, whilst the additional boring device makes the shot holes between these xe2x80x9cfloor and roofxe2x80x9d borings.
The support equipment is preferably provided with pivoting explosion protection shields arranged on the roof caps of its support frames, which are pivoted down into their protecting position before the firing is carried out, so that stones loosened by the firing cannot be projected into the support frame, where they otherwise could damage sensitive equipment within it. Alternatively or supplementary to this the face conveyor can also be provided on its goaf side with vertically adjustable explosion protecting plates, movable in the longitudinal direction of the face.
An advantageous configuration of the invention results if the support equipment is provided with at least one arrangement arranged below the cap of one of its support frames for accepting the boring device and/or the loading device. The demountable boring or loading device from the boring or loading machine can be safely stored on this accepting arrangement between times, whilst the boring and loading machine is either loading the loosened blast rock onto the face conveyor or boring the shot holes. Advantageously several accepting arrangements are arranged, distributed over the mining or face length on the support equipment, so that for conversion the boring and loading machine has only to travel back to the next accepting arrangement for the boring and/or loading device, which is then naturally so far distant from the firing site at the time, that the boring and loading machine is in the safe region of the face during firing.
The boring and/or loading machine has preferably independently driven caterpillar tracks, with which it can travel back and forth immediately on the ground and thus requires no dedicated rail track or similar. In order to improve the loading performance still further, the loading device can have a loading shovel with freeing chisels which preferably can also be activated. It is possible with the aid of the freeing chisels, to separate ridges, unevennesses or similar from the floor still protruding after firing and thus create a practically even floor.
In an advantageous development of the invention the support frames of the support arrangement can be provided with at least one goaf side gob shield with at least one closable opening and associated roof boring device and the support arrangement can be equipped with a goaf side roof fall conveyor. It is then possible via the openings in the roof cap or gob shield of the support frame also to cause the breaking off of mineral rock in the roof either directly with the upwards boring devices or by firing and for instance with the aid of the roof fall conveyor to transport it away. In addition to the face side extraction goaf side extraction can thus also occur which substantially increases the total quantity conveyed.
A second aspect of the present invention is directed to a method of mining using the machine described above, in which:
shot holes are bored in the rock face at right angles to the direction of mining and essentially parallel to the longitudinal direction of the face using the boring device connected to the boring and loading machine;
the boring and loading machine together with the boring device is driven back along the face conveyor to a safe distance from the firing point and re-equipped with the loading device, whilst the firing preparations are made;
following the completion of firing the boring and loading machine, equipped with the loading device is driven forward, in order to load the loosened blast rock onto the face conveyor running parallel to the path of the loading device;
the boring and loading machine with the loading device is then driven back and re-equipped with the boring device, so as then to be driven forward to the (new) rock face, where then new shot holes are bored;
these steps are repeated until the face has been mined over its whole mining length to the depth of the rock face;
the support arrangement, complete with the face conveyor is then moved forward.
An especially advantageous development of the method according to the invention, which achieves independent inventive significance and which can also find application in other forms of long face mining, results if the extraction product breaking out from the roof following the advance of the support equipment is taken away through extraction funnels, drop holes or similar arranged in the floor, into extraction tracks, provided with conveyor devices, extended below the face. It has been shown that in cases in which this pure roof fall exploitation, in which extraction tracks are extended below the ore bed and then extraction funnels or similar are driven through their covers into the bed, permit the extraction of the whole ore bed down to only a comparatively small percentage, by the previous production of a hollow space through the proceeding longitudinal face mining above the extraction tracks the mining can be essentially complete. This is because after the passage of the face, the ore bearing rock can break off into a large pillar-less hollow space and thereby disintegrates into comparatively small pieces, whose extraction through the extraction funnel, drop holes or similar presents no problem. In cases where for instance using the known caving method, seams with a large thickness of 30 or more meters could be mined only to a height of some 10 m and even this could only be partly mined, the combination according to the invention of roof fall exploitation and advancing long face mining permits a practically complete extraction of even very thick seams.
The extraction tracks are advantageously extended parallel to the mining direction of the face, below it. This can occur at two or more levels below the face, if the seam to be mined is especially thick. It is expedient for the extraction tracks to be extended before the long face mining on the face is complete.
Preferably the face can be developed from both face ends using two boring and loading machines at the same time, whereby then the boring and loading machines, following the mining of the whole mining length, are driven back completely to their starting points on the roadway, before the support equipment including the face conveyor is moved. The explosion protective shields arranged on the support frames of the support equipment in the firing area are activated before the firing, so that rock loosened in the firing cannot be thrown into the region of the support frames. For an especially clean bed it has been proved to be advantageous if the boring device at the floor and at the roof bores a multiplicity of closely spaced shot holes.
The extraction product remaining in the roof can be loosened by boring and/or blasting and taken up and conveyed away by means of a roof fall conveyor drawn behind the support equipment and/or via extraction openings in the floor into extraction tracks extended under it.